How to Build an infrared pen

This video is a detailed description of how to make an IR pen. It even shows a diagram and how it works!

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7 Comments

a resistor should be placed in series. Without a resistor, the only limit to the current is the battery's output, which will surely burn out the LED.

The LED has some internal resistance and this setup will work fine for quite a while. However, with some LEDs, it would be better to use 2 AA or 2 AAA batteries (a total of 3 volts) and an 18 ohm resistor.

also, if you use an IR LED and not a visible light LED, you risk SERIOUS injury to your eye.

I think you're talking about UV, or Ultra Violet light.

I don't know where you get this from. Your TV remote throws out IR light all of the time. I've never heard of anyone injuring their eyes.

if you have a hard time making this pen - you can buy one from this site: http://infraredpens.com/

You can also buy on ebay, I hear user shakespeare1212 on ebay makes great pens. :-)

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